Motor-control system



July 29, 1930.

N. L. MORT ENS EN ET AL MOTOR CONTROL SYSTEM Fi led May 25, 1928Patented July 29, 1930 UNITED STATES PATENT OFFICE NIELS L. MOBTENSEI-T,OF MILWAUKEE, AND CARROLL STANSBURY, OF \VAUWATOSA, WISCONSIN,ASSIGNORS, BY MESNE ASSIGNMENTS, TO CUTLER-HAMMER, INQ, OF MILWAUKEE,WISCONSIN, A CORPORATION OF DELAWARE MOTOR-CONTROL SYSTEM Applicationfiled May 25,

This invention relates to motor control sys terns, and is especiallyapplicable to multivolt-age systems, although not limited thereto.

In such systems wherein the motor is subjected to field'regulating,difliculties have been experienced as the result of too great a fieldstrength when transferring from one voltage to a lower voltage, and uponinitiation of dynamic braking. On the other hand, full field strength isdesired both for starting and dynamic braking, and ordinarily the fieldcon trol must be automatic for acceleration, deceleration and stopping.

The present invention has among its objects to provide a multi-voltagesystem wherein the control of the motor field is entirely automatic andwherein field weakening may be obtained for transfer from one voltage toa lower voltage and also for initial dynamicbraking.

More particularly, the invention has among its objects to provide meanswhich will afford full field strength as desired, but which will insurea sufiiciently weakened field at the instant of transfer from onevoltage to a lower voltage or establishment of dynamic brakingconnections, as the case may be, and for a temporary period thereafter,to overcome the difliculties heretofore experienced.

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawing illustrates di- I agrammatically certainembodiments of the invention which will now be described, it beingunderstood that the invention is susceptible of other modifications andother applications falling within the scope of the appended claims.

In the drawing Figure 1 is a diagrammatic View of a controller embodyingthe invention in one form, and

Fig. 2 is a diagrammatic view showing a 1928'. Serial No. 280,454.

or alternatively from a higher voltage circuit L If. It may be assumedthat this motor is employed for drive of a tire building machine andthat the circuit L L is 115 volts, while the circuit L L is .430 volts,these being the customary voltages for such machines. V

The controller includes electroresponsive reversing switches F and R, anelectroresponsive switch L to connect the motor to the low or voltagecircuit through said reversing switches and a resistance r, and anelect-roresponsive switch H to connect the motor to the higher voltagecircuit through said reversing switches and a resistance 1' Thereversing switch F has main contacts 1 and 2 and normally closedauxiliary contacts 3, while reversing switch R has main contacts l and 5and normally closed auxiliary contacts 6. As will be understood, themain contacts of the reversing switches commutate the motor armatureconnections for reverse operation thereof, while the normally closedcontacts 3 and 6 control a dynamic braking loop across the motorarmature inclusive of a braking resistance 1*. The switch L is shown asof the double pole type having contacts 7 and 8, and the switch H isshown of a like type having contacts 9 and 10. lVhile the switches L andH have both poles thereof located at one side of the motor armature itis of course to be understood. that each might have its poles on.opposite sides of the motor armature.

The motor field is connected across the higher voltage circuit L Lthrough an adjustable rheostat- 11 having a short-circuit controllableby an accelerating relay All of the vib 'ating' t pe having nomal v opecontacts 12 and having its win l with the motor armature. Sue lcustomary provision of the controller illustrated, ano as wii respondsupon con'ipletion of "he notor cue-nit to short-circuit he field r 2whereas motor normal fter vibrating unti motor attains tun 1n theparticular controller illustrated no provision made for accelerating themotor through armature control when comected to the lower voltagecircuit, but provision made for accele ating the motor through armaturecontrol prior to acceleration through field control when the motor isconnected to the higher voltage circuit. This means shown as comprisinga so-callec lockout switch LO having contacts 113, an operating windingl a lockout windingand a holding winding 16. The operating and lockoutwindings 1% and 15 connected in series with the motor to afford currentlimitcontrol of the contacts which upon enga r ing short-circuitresistance r together with windings ll and 15. winding 16 holds the con.cts 13 in engageiner said winding being of the shunt type to beconnected across the line through a resistance 1 upon closure of switchH.

The arrangement thus far descriled. which is well knowr provides for thedesired acceleration and would ailort a wealici'ied held fordeceleration but would not insur held strengthening for low voltageoperation aft 4 transfer or field strengthening for dynamic braking.However. additional field controlling meal s are provided whicl togetherwith the foregoing means atlord co nplete and entirely automatic controlof the motor held.

Such additional field controlling means; compris is a voltage relay Vhaving normally engaged contacts 17 paralleli the contacts 12 of therelay All to short-c1 cuit the held rheostat 11. 1e winding' of relay "Fis connected across the motor armature through the resistance 1* andhence is adapted up n accoloration of the motor to a given degree todisengage contacts 1'? and to maiitaii. the same disengaged until themotor speed is reduced to a given value. Preferably the relay V isdesigned and adjusted to respond only when the motor speed is such as tosubject the same to approximately 230 volts ant. to hold the contacts 17disengaged until the voltage to which it is subjected is reduced toapproximately 115 volts.

lVith the r lay V thus adjusted the same would not respond unti atterranster the motor to the higher voltage circuit and hence it wouldrender the relay inefective to weaken the motor field during low voltageLcceleration 01" the motor to normal speed after such transfer. Also therelay V woul mai itain contacts 17 disen gagged upon transfer from thehigher voltage circuit to the lower deceleration of the 1 voltagecircuit gending;

notor. Accordingly with i All open the relay V would upon decelerationinsure field weakening during tans'ter oi the motor from the highervoltage rcuit to the lower voltage circui and for a Imorary periodthereafter. However, the

' would lelGZlSE upon a given decele 'athe motor as previouslydescribed, reengaging contacts 1"? to short-cirl eiield rheostat andhence provide full field strength of the motor tor continued low voltageoperation.

Furth r, should the motor be disconnected 'i'lfOll'l circuitandsubjected to dynamic bra ino; while op -rating a speed suiticicnt tomaintain rel V energized said relay would function act forth to maintainthe cona ts 1? disengaged for tield vealrening for tmporary period. Withthe connections rstrated release of relay V would be Sill t a delay byself-inductance for the ring at rid relay "s l rt-circuited by k. I 1 S1liary contacts of the reversing;

the other hand contacts 1. to reestablish around the rhcostat 11 by "51the motor field rongth for continuel dynamic br l we'll .J A mastersuite 1 20 ot us.-

k Or the L through a switch 21 wh'ci may be asoperat ruined to be thefoot monly employer. in tire macl circuits controlled by masts ma y 1 tocontact 92 and segnunt 23 5 0 conductor to the winding ilch n. oralternatiicl from segment igh contacts 26 by conductor QTto the eh ll,both of said windings "I: d by conductor 2? through 0 I13. llso. circuitmav be nent 23 ot the n'iaster switch through contacts 29. certain ofwhich are duplicated. by conductor 30 throuoh the winding: oi switch Lto conductor 28 and thence to line L, and from segment 23 +1. 1 tn 4T. 1-F Th 1 no .1 tonnes u Lei n or u 401 are duplicated by conductorthrough the winding of switch H to (UilClHCiLOl' 28 and thence to lineL.

'lhe motor connections follows:

rem line L through contacts 2 of reversing switch F by conductor 38motor armature from right to ductor l through cont .s l. of switf hyconductor through Winding e lay AR and a resistance 1' through contacts7 and 8 of switch L to line L or altern from Winding of relay hit byconductor 5o through the resistance r and windings 15 and M to andthrough contacts 9 and 10 of switch H to line L. Alternatively circuitmay be t need from line L by conductor 'hrough contacts 5 of reversingswitch R to 111d. through the motor armature from left. to right, byconductor through contacts to conductor and thence to line L or line Las previously traced. The motor circuit may be trac d from line L thrugl. said field and rheostat 11 or the short-circuit thereof to line L.

Referring to the modification shown 2. the winding of relay J isconnected across the motor armature throitigrh a resistance and isprovided with a nor; ally open Sll( 1t*Ci1"- cuit controlled by contacts39 of a relay AP having its Winding connected in the dynamic brakingcircuit. WVith th Windin V so connected it remains energized uponestablishment of dynamic braking connections until the relay AP res'ionds, and l relay so designed. and adjusted as to respond only afterdynamic braking has started. Accordingly the relay V .vould function tomaintain a weakened lleld strength for a longer period than is providedfor by the connections Fig. l, and the delay in release of relay V wouldbe slightly augmented by the shortcli around its u" ling established byrelay upon responding. On the other h lease of rel-1,; V is insuredafter a. temporary pried to afford lull field str h for continueddynamic braking.

Referring; to the further n'iodification shown in Fig. 3 a relay AF isprovided in lieu of relay V of F' 1. Relay AF mallv closed contacts 40to short-circuit the field rheostat and has its Windi1i so connected. asto be responsim to the cour er volt use of the motor to ellectinterruition o.. the short-circuit around the field rheostat upon accelerationof the motor to a I speed. More pal-ti ularly the d relay AF has oneterminal 6011110614. side of the motor armature througi h ance rassi'uniug closure of: eit ier reversin switch and has its othertern'iinal connect through. a resistance r to L and hence to theopposite side of the motor armature as suming closure of eitherreversing Further, the winding of relay AF 11 a a. circuit to hecompleted. by cc itact 1' switch L whereby said relay is renderedresponsive so long L to the low voltage circuit and wherebyenergiziation of said relay tollowin of the motor from the higher volt;

through the f, il im as the motor is conn cted to the lower voltagecircuit is insured. However the t "tioned connec ons of said relayinsure agi' re ease of saio relay during such transier zssur operationof the motor above a of said I 23 n speed and rel.

relay further delayed by its self-inductive action ugon shor .g of itsWinding by contacts *2 5 Thus relay AF provides for maintaining thefield strength of the motor upon t'anste of the motor from the highervoltage circuit to the lower voltage circi'ut and said relay has anadditional. connection tor its Wind ing Where it also fu ctions to delayfield ital.. d namic It "s i icularly the XV; H ha a i ci iit in- SllOlxl tance and tons a orded Accordino'l as will he i energiael when circuitand would remain 5 period to allord aritv to slow down prior v 1! cloing a discharge circuit. understood t the motor io relay r ontinueddynamic W and desire to secure niotoiz, supply cirerent voltages meansto 7 rom either circuit to the oiling iieans .1 cults therefor oftdiil'erent goo means to transier said motor ther circuit to the otherand autoni controlling i'ielu u'ealzero T1 in 01' S511 lllOliGl I i e .Aw h i 101 in 5111; C1 ilulfi A,

id circuits another of lower vol" to i oer; peiiod thereafter, helflpllfi 'nga i ayhiasedto then ng and having o uoiected e counter Incombine i tor oidi ontrolliii means 2' clay to he in re I, motor supplycirliereut v ges, automatic 1.01 said motor includponse to counter olior'joifield weal-zoning to coni'icct said motor to selectively oralternatively dynamic and remove said is counter voltnot Iii supplycirvoltaees, means to 1 cans fol relay responsive h l i Q voltage oi themotor and a rethe motor current, said recoacting to provide for fieldweakening and automatic field controlling motor comprising a acc erationof said motor and on said motor from one oi said 1 ends to another oflower voltage.

combination a motor, upply cir- *efor of dniercnt vo means to s. ldmotor to said circuits selective- ,g; means for connprising a relayresponsive to or vol ge of the motor and a relay JQSQOllSlVG to themotor curr nt, said relays coactingto provide for field weakening uponacceleration oi said motor and on transfer of said motor from one ofsaid circuits to another of lower voltage, one said first mentined relayproviding for field strengthening upon deceleration of said motortollowingsuch transfer.

6. In combination, a motor, supply circuits therefor of differentvoltages, means to connect said motor to said circuits selective- I 1yor alternatively to disconnect said motor and establish dynamic brakingconnections therefor and automatic field controlling means for saidmotor comprising a relay responsive to counter voltage of said motor anda relay responsive to the motor current, said relays coacting to providefor field w a rening' on acceleration and under certain speed conditionsalso providing for field weakening when said motor is transferred fromone of said supply circuits to another or" lower voltage or when saidmotor is initially subjected to dynamic braking.

7. In combination, a motor, supply circuits therefor of differentvoltages, means to connect said motor to said circuits selectively oralternatively to disconnectsaid motor and establish dynamic brakingconnections therefor and automatic field controlling means for saidmotor comprising a relay responsive to counter voltage of said motor anda relay responsive to the motor current, said relays coactina' toprovide for field weakening on acceleration and under cert-aiz speedconditions also providing for fielt-i weakening when said motor istransrerred from one of said supply circuits to er of lower voltage orwhen said motor 'tia y subjected to dynamic braking, ield controllingmeans for field str iii-edium of said first in such transfer of ofdynamic braking.

S. The combination with a motor, of means to connect said motor to asupply sourcse, or alternatively to disconnect said motor from itssource of supply and establish dynamic braking connections therefor,

further providig'thening through the mentioned relay toll said motor orinitiation

